Background Art
Modern day aircraft, and particularly modern day military aircraft, typically make use of a large number of actuators, sensors, modules and other components. These components produce, or can be monitored to obtain, signals indicative of their performance during takeoff, landing and other aircraft flight phases. Often one or more aircraft components are monitored and/or controlled by a module called a "line-replaceable-unit" (LRU). An LRU is a highly complex module often incorporating several processors for controlling and/or monitoring one or more components or subassemblies of an aircraft. An LRU may be provided to monitor and/or control one or more external devices such as an actuator, valve, motor, etc., associated with a particular component or assembly of the aircraft. An LRU typically also generates output signals which can be monitored to determine if the LRU and/or the component with which it is associated is not operating properly. Examples of some of the LRUs associated with a C-17 aircraft are listed as follows to provide an appreciation as to the wide ranging and diverse functions of a typical military aircraft which the LRU's are responsible for controlling:
______________________________________ System/Component (AF nomenclature) Acronym ______________________________________ Emergency Egress Sequencer ES Aerial Delivery Locks Control Panel ADLCP Cargo Delivery System Control-Status CDSCSP Panel Aerial Delivery System Controller ADSC Aircraft Fault-Function Indicator Panel AFFIP Sensor Signal Interface SSI Antiskid-Brake Temperature Monitor ABTMCU Control Unit Electronic Engine Control EEC Electronic Engine Control (for Auxiliary EEC Power) Auxiliary Power Unit Control Panel APUCP Environmental System-Fire Detection ESFDCP Control Panel Temperature Control Panel TCP Environmental Control System ECSC Controller Manifold Failure Detection Controller MFDC Cabin Pressure Controller CPC Cabin Air Pressure Selector Panel CAPSP Windshield Anticing Control Box WAICB Window Defogging Control Box WDCB Battery Charger no acronym Generator Control GC Electrical System Control Panel ECP (Electrical Control Panel) Static Frequency Converter no acronym (60 Hertz Converter) Static Power Inverter no acronym Bus Power Control Unit BPCU Hi-Intensity Wingtip Lights Power no acronym Supply (no AF nomenclature) Upper & Lower Beacon Light Power no acronym Supply (no AF nomenclature) Power Supply-Dimming Unit no acronym Battery Charger Set no acronym (Emergency Lighting Battery/Charger) Hydraulic System Controller HSC Hydraulic System Control Panel HSCP Fuel System-Engine Start Control FSESCP Panel Liquid Quantity Indicator LQI Ground Refueling Control Panel GRCP Fuel Quantity Computer FQC Fluid Purity Controller FPC Bearing-Distance-Heading Indicator no acronym Engine-Thrust Rating Panel Display ETRPD Signal Data Recorder no acronym (Quick Access Recorder) (QAR) Standard Flight Data Recorder SFDR Propulsion Data Management PDMC Computer (Aircraft Propulsion Data Management (APDMC) Computer) Flight Control Computer FCC Actuator Flight Control Panel AFCP Automatic Pilot Control-Indicator APCI Ground Proximity Warning Control GPWCP Panel Spoiler Control-Electronic Flap SCEFC Computer Display Unit DU (Multi Function Display) (MFD) Multifunction Control Panel MCP Air Data Computer ADC Inertial Reference Unit IRU Head-Up Display Unit ("Glass-cockpit" HUDU Display) Digital Computer DC (Mission Computer) (MC) Display Unit (DU) (Mission Computer Display) (MCD) Data Entry Keyboard DEK (Mission Computer Keyboard) (MCK) Intercommunications Set Control ICSC Intercommunications station no acronym Audio Frequency Amplifier no acronym Public Address Set Control no acronym Cordless Headset no acronym Radio Receiver-Transmitter no acronym CargoWinch Remote Control no acronym Battery Charger no acronym Communication-Navigation Equipment CNEC Control Communications Equipment Control CEC Central Aural Warning Computer CAWC Warning And Caution Computer WACC Warning and Caution Annunciator WACAP Panel Signal Data Converter SDC Coder Decoder Keying Device CDKD Transponder Set Test Set no acronym (I-Band Transponder Test Set) (TTU) ______________________________________
It will also be appreciated that aircraft such as the C-17 aircraft include a wide variety of actuators and sensors that provide output signals that can be monitored and recorded, but which do not have an LRU associated therewith. These components include, but are not limited to electrical and electromechanical actuators, valves, transducers, sensors, etc. Thus, it will be appreciated that most modern day aircraft, and especially modern-day military aircraft, have an extremely wide number of diverse components which are monitored to help insure proper operation.
With previously developed monitoring and testing systems, information from the LRU's and other components of an aircraft have been recorded on a quick access recorder (QAR). The quick access recorder records the information from the various LRU's and other components which are being monitored and stores the monitored information on a magnetic tape storage medium. Due to the inherent limitations of all magnetic storage media, some of the stored information may become corrupted. In some instances this might lead to inconclusive or erroneous fault indications should the magnetic storage medium indicate that, for example, a particular LRU has provided output signals indicating that a component associated therewith is malfunctioning when it is not.
Various systems for recording and/or analyzing operational parameters of various LRU's and other components of an aircraft are disclosed in the following U.S. patents, the disclosures of which are hereby incorporated by reference:
______________________________________ 4,943,919 4,635,030 5,019,980 4,729,102 5,218,547 4,788,531 5,267,147 5,500,797 5,386,363 5,541,863 4,604,711 5,552,984 ______________________________________
More recently, an optical quick access recorder (OQAR) has been used on board aircraft to record the information output by the LRU's and other components of the aircraft on an optical storage medium such as a high density optical storage disc. The optical storage disc tends to be far less susceptible to corruption than magnetic storage media and can hold a much greater amount of information than can be held by magnetic storage media. This has enabled even more information to be recorded (much of it in real time) pertaining to the various operational parameters of the aircraft and the performance of the wide ranging and numerous components, sensors and actuators of the aircraft than was possible with magnetic storage media.
Up until the present time, information recorded by the optical quick access recorder has only been used to generate information which indicates whether or not signals from the LRU's and other components of the aircraft are indicating fault conditions. Put differently, the information provided by the optical quick access recorder has not been used to determine if the fault indication is in fact a spurious fault indication. Up until the present time, information obtained from the optical quick access recorder generally has required highly trained service personnel to first interpret that a fault condition exists with a certain LRU or other component of the aircraft, and then either perform on-board testing that utilizes the aircraft as a test device or physically remove the effected component from the aircraft for diagnostic testing. Sometimes, diagnostic testing may not identify a problem with the LRU or other component. Often, the diagnostic testing of a removed LRU can consume several hours by a highly trained service person in an effort to determine the cause of the fault indication. In some instances, the effected LRU or component is eventually reinstalled in the aircraft without ever being able to determine what caused the initial fault indication. This has led to high "cannot duplicate" ("CND") and/or "no-fault-found" ("NFF") rates for various LRU's and other components.
Two challenges have underscored the high NFF rate: 1) the same LRU often makes repeated back-shop visits and can lead to "intermittent failure" troubleshooting (Intermittent testing often results in days of troubleshooting since a several hour fault detection test is repeated several times); or 2) Service personnel may become sensitized to repeated NFF test results. Since testing of an LRU or other component may take considerable effort using specialized equipment and skills, it will be appreciated that significantly reducing the incidence of no-fault-found results of diagnostic tests can represent a very significant cost savings. The following table illustrates test times required for determining if a fault condition exists for 38 LRU's of the C-17 aircraft by McDonnell Douglas using automatic test equipment.
______________________________________ LRU ETE Run Time (From technical order, includes the 10 Minute LRU Name LRU Acronym Setup/Teardown time) ______________________________________ Aerial Delivery Locks ADLCP 28 min. Control Panel Cargo Delivery System CDSCSP 52 min. Control-Status Panel Aerial Delivery System ADSC 40 min. Controller Sensor Signals Interface SSI 30 min. Antiskid Brake Temp ABTMCU 40 min. Monitor Controt Unit Electronic Engine EEC 40 min. Control Environmental System- ESFDCP 80 min. Fire Detection Control Panel Environmental Control ECSC 160 min. System Controller Manifold Failure MFDC 50 min. Detection Controller Hydraulic System HSC 60 min. Controller Hydraulic System HSCP 40 min. Control Panel Fuel System-Engine FSESCP 60 min. Start Control Panel Liquid Quantity Indicator LQI 22 min. Ground Refueling GRCP 78 min. Control Panel Fuel Quantity Computer FQC 103 min. Fluid Purity Controller FPC 60 min. Engine Thrust Rating ETRPD 31 min. Panel Display Propulsion Data PDMC 50 min. Management Computer Flight Control Computer FCC 316 min. Actuator Flight Control AFCP 36 min. Panel Automatic Pilot Control APCI 120 min. Indicator Ground Proximity GPWCP 40 min. Warning Control Panel Spoiler Control- SCEFC 280 min. Electronic Flap Computer Display Unit DU 210 min. Multifunction Control MCP 60 min. Panel Air Data Computer ADC 114 min. Head-Up Display Unit HUDU 180 min. Digital Computer DC 219 min. Display Unit DU 35 min. Data Entry Keyboard DEK 40 min. Intercommunications Set ICSC 27 min. Control Communication- CNEC 35 min. Navigation Equipment Control Communications CEC 80 min. Equipment Control Central Aural Warning CAWC 50 min. Computer Warning And Caution WACC 44 min. Computer Warning and Caution WACAP 25 min. Annunciator Panel Signal Data Converter SDC 315 min. Coder Decoder Keying CDKD 180 min. Device ______________________________________
It would therefore be highly desirable to provide some method of analyzing and automatically reporting information for making a preliminary determination as to whether a fault indication provided by an LRU or other component of an aircraft is in fact a legitimate fault indication which will require further diagnostic testing of the LRU or affected component, or which is a spurious fault indication. In the case of a spurious fault indication, the LRU or component under investigation would not have to be either tested on-board the aircraft utilizing the aircraft as a test device or removed from the aircraft and subjected to several hours of testing in an effort to duplicate the fault condition or to find a malfunctioning subcomponent or subassembly of the LRU or other component. Accordingly, such a method could significantly reduce the instance of wasted man hours attributed to both on and off-aircraft testing of LRU's and other components of an aircraft which are, in fact, in perfect working order, but which have provided output signals which may indicate that same are not operating properly.
It would also be highly desirable to provide a method for recording and analyzing information from a bulk storage device, which provides user readable information enabling service personnel to quickly determine whether various LRU's and other components of an aircraft are operating within acceptable operating parameters without the need for using a variety of different computers and equipment, and without the need for requiring computers to be taken on board the aircraft to download information from various on-board computers of the aircraft.
It would also be desirable to provide a method for recording and analyzing information from an aircraft which can quickly enable service personnel to determine if one or more LRU's of the aircraft or other components need to be removed for further diagnostic testing, and which also enable qualified service personnel to quickly determine if information from an LRU or other component which appears to suggest a fault condition is in fact explained by the presence of other signals which verify to the service person that no fault condition exists with the particular LRU or component under investigation. Most preferably, this failure filtering technique would be automatically reported to service personnel.
It would also be highly desirable to provide a method for automatically condensing what is recorded, as necessary. Current maintenance recorder maps have finite memory capacities and preclude the (real-time) capture and recording of all available fault data. This has often prevented a significant portion of LRU fault data from being recorded since a minority amount of LRU data can fill the entire maintenance recorder map space. Therefore, a method that automatically condenses what is recorded and automatically updates any condensing as needed, can support the above desirable method reporting while finite recorder map limitations exist.